This invention relates generally to gas turbine engines and, more particularly, to means for providing radial support for the turbine components of a gas turbine engine.
Turbine efficiency is largely determined by the ability to maintain a close clearance relationship between rotating blades and the surrounding stationary shrouds. Accordingly, in order to achieve and maintain good performance, it is necessary to have well maintained and repeatable close tolerances between those components. Wide clearances represent performance losses; and interference relationships, which may be caused by circumferentially nonuniform mechanical or thermal radial loads, tend to cause nonuniform wear of the shroud which subsequently may result in degraded performance. It is therefore desirable that the shroud be kept round and relatively isolated from such circumferentially nonuniform mechanical and thermal radial loads.
In an effort to limit the number of parts and simplify construction of a gas turbine engine, it is desirable to have a single support structure for supporting both the turbine shroud and the turbine vane immediately upstream thereof. For the reasons stated hereinabove, it is also desirable to have close tolerance radial positioning of the shroud. The vane, on the other hand, requires support only in the axial direction since the radial positioning thereof can be provided by other structure. However, because of the high axial loading, and especially at high speeds, any radial movement of the vane may be transmitted to the support structure and hence to the supported shroud to thereby effect its critical position. Nonuniformity in the circumferential shape of the shroud can thus result from nonuniform radial loads (as caused by either mechanical or thermal disturbances) which are transmitted from the vane to the shroud by way of the support structure.
It is therefore an object of the present invention to provide a turbine shroud support structure which maintains close radial tolerances and circumferential uniformity of the shroud.
Another object of the present invention is the provision for a support structure which provides both close tolerance radial positioning of a turbine shroud and axial positioning of an associated vane.
Yet another object of the present invention is the provision in an axial support structure for a turbine vane for preventing radial movements from being transmitted from the vane to the support structure.
Still another object of the present invention is the provision in an axial support structure for a vane for the isolation of certain portions of the support structure from thermal gradients which may occur at other portions thereof.
A further object of the present invention is the provision for a joint vane and shroud support structure which is economical to manufacture and effective in use.
These objects and other features and advantages become more readily apparent upon reference to the following description when taken in conjunction with the appended drawings.